An engine of a hybrid vehicle may propel the hybrid vehicle or provide energy to charge a battery of the hybrid vehicle. The engine may have a broad operating range such that the engine may be operated across a wide range of engine speed and torque conditions. However, it may be desirable to operate the engine at its most efficient operating conditions to conserve fuel. One way to ensure that the engine is operating efficiently is to adjust engine operating conditions so that the engine operates at conditions where it is most efficient. Nevertheless, varying driver demand power and road conditions may make it difficult for the engine to stay in an operating range where its fuel consumption is lowest. As a result, the engine may be operated outside of a low fuel consumption operating region to meet driving conditions. The vehicle's fuel consumption may increase greater than is desired if the vehicle is operated outside of low fuel consumption engine operating conditions for more than a threshold amount of time.
The inventors herein have recognized the above-mentioned issues and have developed a powertrain operating method, comprising: providing a first relationship between driver demand power and requested powertrain power via a controller in an engine power region between a first engine low fuel consumption operating region and a second engine low fuel consumption operating region in a first operating mode; providing a second relationship between driver demand power and requested powertrain power via the controller in the engine power region in a second operating mode, the engine power region a higher engine fuel consumption region than the first and second engine low fuel consumption regions; and operating an engine in response to the first and second relationships.
By providing different relationships between a driver demand power request and an engine power request, it may be possible to transition engine operating conditions between a first engine low fuel consumption region and a second engine low fuel consumption region faster. For example, a change in requested engine power versus requested driver demand power may be increased for an engine operating region that lies at engine speed and torque values that are between engine speed and torque values for two low engine fuel consumption operating regions. Consequently, a driver may transition or move from a first low engine fuel consumption operating region to a second low engine fuel consumption operating region in a shorter period of time to improve vehicle fuel economy.
The present description may provide several advantages. Specifically, the approach may provide increased powertrain efficiency. Further, the approach provides feedback to a driver that may help to increase vehicle fuel efficiency. Additionally, the approach may utilize a motor in conjunction with an engine to improve vehicle drivability.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.